UNE-EN ISO 28706-3:2018

This part of ISO 28706 describes a test method for the determination of the resistance of vitreous and

porcelain enamelled articles to attack by alkaline liquids at temperatures between 25 °C and 95 °C. The

apparatus used is a hexagonal vessel in which six enamelled specimens or a tetragonal glass bottle in

which four enamelled specimens are simultaneously tested.

NOTE 1 The resistance to any alkaline liquid can be determined. However, the test method was originally used

for the determination of the resistance to hot detergent solutions, within the neutral and alkaline range, used for

washing textiles.

NOTE 2 Since detergents are continually subject to alterations in their composition, a standard test solution

is specified which, in respect to its alkalinity, wetting properties and complexing behaviour, can be considered

as a typical composition for the detergents at present on the market. The pH value and alkalinity of the standard

test solution depend on the proportions of sodium tripolyphosphate, sodium carbonate and sodium perborate

present; sodium tripolyphosphate acts simultaneously as a complexing agent. The wetting properties of the

standard test solution are obtained by the addition of alkylsulfonate. A higher sodium perborate content is not

considered necessary since the effect of oxygen on enamel is unimportant and an increase in the perborate

content does not cause any significant alteration in the alkalinity of the standard test solution. The testing of

different enamels using this standard test solution and other test solutions (including 5 % sodium pyrophosphate

solution) has justified the use of this standard test solution for determining the resistance of enamels to hot

detergent solutions.